This invention relates to an effective product quality information management system for products with little variation in quality characteristics for each manufacturing process. More specifically, this invention relates to a product quality information management system which determines pass or fail of the product quality of production batches based on the results of inspections and non-experimental inspections defined in the standards and which can control product quality in a product quality analysis which includes inspection items analyzed with different frequencies.
Conventionally, in the manufacturing industry and the like, products manufactured in-house are usually inspected according to a defined product standard. In such a quality inspection, statistical variations may differ for each inspection item. Whereas an inspection item with a large variation requires inspection of all batches, an inspection item with a low variation provides a statistical guarantee of quality even if the inspection frequency is low.
Thus, the analysis inspection frequency may be different for each item. For example, some inspections are performed on each production batch but other inspections are performed once a month, once a week or every day.
The inspection results document is a document on which inspection results for each quality characteristic are printed, and inspection results can be viewed on it. At the same time, the inspection results document is also a certificate which guarantees to the customer that the product having the specified mass (or capacity) of the product batch has passed inspection.
In the inspection results document, a manufacturer is also required to guarantee the product standard according to the analysis frequency.
In the prior art, when inspection results documents were issued for products having a different analysis frequency, a large number of data which were unnecessary to statistical calculation of the results, i.e., a large number of identical data, were recorded, and this appeared as inspection items with a small amount of variation.
In recent years, great demands are being made of manufacturers regarding their products, and records of inspection results documents for a manufactured product are the only proof which shows a manufacturer has not been negligent in the event of an accident or problem. However, if there is an erroneous entry by an inspector in the inspection results documents, there is not only the problem that the records cannot be used as proof that the manufacturer was not guilty of negligence. There is also the problem that, if defective products are shipped which are outside standard and tolerance values, and an accident or problem occurs due to their use, the manufacturer may have to take full responsibility. In view of the possibility of such a situation arising, the manufacturer must construct a reliable quality control system.
It is therefore an object of this invention to provide a product quality information management system which can make an overall pass-fail decision for every product batch on the quality of products with different inspection frequencies.
The product quality information management system according to this invention is a system which determines pass or fail by comparing an input product inspection result with a product standard, comprising an input device for inputting a product inspection result and an inspection frequency for each inspection item, an inspection result storage device which stores the product inspection result input from the input device, a product standard storage device which stores a product standard for each inspection item, an inspection item determining means which selects the inspection item, determines the presence or absence of a required product inspection result input for each inspection item and selects a product inspection result of a previous batch based on the product standard stored by the product standard storage device, and the inspection frequency input from the input device, and a pass-fail decision means which compares the product inspection result input from the input device and past product inspection result selected by the inspection item determining means with a product standard for each inspection item and performs an overall determination to determine pass-fail of the product.
It further comprises an issuing device which gives an inspection result document number only to a product which has passed the inspection by the pass-fail decision means, and issues an inspection result document, an inspection result document storage device which stores the issued inspection result document as electronic data, a search means which searches inspection result from the inspection result document number, and a write-once storage device which stores the issued inspection result document as electronic data on a write-once recording medium.
Therefore, pass-fail of product quality of products with different inspection frequencies can be determined by inspections according to product standards and inspection results for other batches measured in the past, which can be used for quality control of products with little variation in quality characteristics in the manufacturing steps.